1. Field of the Invention
The present invention relates to a process and a device for spraying a liquid product, especially a liquid fuel, into a working space. It applies in particular to the burners for glass melting furnaces.
The pressures which are referred to below are relative pressures.
The invention relates especially to a process for spraying a liquid product into a working space, of the type in which a prespraying of the liquid product is carried out inside a prespraying space other than the working space and a spraying of the presprayed mixture is carried out by making use of a gaseous spraying stream.
The invention also relates to a device for spraying a liquid product into a working space external to the said device, of the type comprising means for prespraying the liquid product, means for feeding the prespraying means with liquid product to be sprayed and means for spraying the presprayed mixture.
2. Description of the Related Art
Processes and devices making it possible to spray or atomize a liquid fuel, especially heavy fuel oil, into fine droplets are known. These droplets, brought into contact with an oxidant, for example oxygen, enable a flame to be maintained.
The characteristics of the flame obtained at the outlet of the spraying device depend on the quality of the spraying of the liquid, in particular on the size of the droplets obtained and on the statistical distribution of their diameters. Furthermore, the nature of the flame obtained also depends on the speed of ejection of the sprayed fluid at the outlet of the spraying device.
Depending on the spraying characteristics, the flames obtained may be soft or hard and may be attached to the end of the spraying device or else detached.
Furthermore, in the application to glass melting furnaces, a device for spraying a liquid fuel must be fit to resist the high temperatures of the order of 1400.degree. C. to 1700.degree. C. prevailing in the furnace. In particular, such a device must be capable of withstanding these temperatures for a certain period of time when it is not in operation. The known spraying processes and devices satisfy the conditions described above only in an imperfect or partial manner.
For example, there is a known spraying device with twin atomizing, comprising a first prespraying chamber into which a prespraying fluid and a liquid fuel are introduced. The outlet of this prespraying chamber opens into a second spraying chamber comprising entry openings for a gaseous spraying stream. The outlet of this second spraying chamber opens into the working space in which the sprayed fuel is inflamed. Such a device presents an explosion risk due to the presence of sprayed fuel in the two consecutive internal spraying chambers, the last one of which is in communication with the working space where the flame is established.
Furthermore, this device is very poorly protected against attack by heat.